Right...
The reason people point out her face changes (although it can be very annoying) is simple. Britney's face did change. Small cosmetic face changes can really change how you perceive someone's face overall. The biggest reasons for her change in 'Britney face' is the fact that she got obvious lip injections in her top lip (which often rids people of their cupid bow and a bit of face expression) and face fillers.
Subtly enlarging areas around the nose give the illusion her nose is slightly smaller, hence people start discussing nose jobs.
Are these things important? No.
Is it THAT big a deal if someone mentions it in a non-derogatory way? Meh, not really.
Her fan base have became sometimes unnecessarily defensive.
Saying that, she CAN do whatever she likes to her own body and face - it really is not that big of a deal.
I just hope she's not just doing it because 'it's her job to look good'. That'd be a shame.

Honestly, even if you weren't to like her music, Britney has something about her personality that appeals to most people. Most people like Britney. And even though her life is so different from most people, most people still feel they can relate to her. That doesn't come around often.
...and she makes good music.

"The somewhat grungy look was a far cry from the family-orientated side of herself she showed of herself over the weekend"
It's a mystery... when will Britney show of herself her other side of herself which she shows of, behind and around herself be shown?

Oh, of course. Once they'd finished describing the picture they started describing her last instagram video in detail... which they also posted
They didn't refer to her legs as 'pins' in this article though. Someone must be filling in.

Did the rumours not say that they split up a while ago? Weren't they seen together last week? I think it's possible someone saw the fact that they hadn't been pictured together in a while as a good opportunity to be a 'source'

Whenever I've tried to introduce her to people I've always just happened to gravitate away from the singles for some reason. Sometimes I get 'Oh, this is Britney? Interesting...' And they end up liking it. I think most people know at least some of her singles, so I think if someone doesn't really think they like her then maybe they'd be better off giving her 'less known' stuff a chance. I like to let people here Early Mornin', The Hook Up, Get Naked, Mannequin, Passenger, Gasoline...
and Toxic. They all like Toxic. (although I'd more likely show someone a video of her performing Toxic live rather than just listening... watching her dance is part of the Britney experience!)

It was probably just one of those 'say what the interviewer wants to hear' moments.
Although I will say, she did seem quite sure of what she was saying for a mere 'Yeh, Sure, Whatever' type moment... this could just be due to her being pre-prepared to answer though. "Britney Spears doesn't have any plans to come to China!" isn't the most exciting interview description.

Music taste is way too subjective for this question to have a definite answer. It's a good song though. And God, it's SO GOOD work out/dance to. One of the best, I think. It came on during the warm up in my dance class a couple of weeks ago and it got everyone's adrenaline going more than any other song that was played. Everyone loved dancing to it.